Wooden Portcullis Pack
A pack of 10 wooden portcullis[en.wikipedia.org] in different sizes (2m x 4m, 2m x 6m, 3m x 5m, 3m x 8m, 4m x 6m, 4m x 9m, 5m x 9m, 5m x 12m, 6m x 9m, 6m x 12m). They fit most medieval or so gates found on the workshop (see screenshots above). Should they not fit your purpose, feel free to use Procedural Objects.
In game, these are props that can be freely elevated using MoveIt!. Search for "portcullis" with FindIt! to find them. They have custom thumbnails to ease your search.
Technical Stuff:
Main Meshes: 152-504 Tris, 128×512 Textures
LODs: 16-40 Tris, 64×64 Textures
Textures are shared across all versions, so actual RAM-usage should be about a tenth of the pack size with Loading Screen Mod.